Spark-plug.



L. R. SPENCER.

SPARK PLUG.

APPLIOATION FILED JAH.14, 1911.

Patented Apr. 4, 1911.

g 4 a 5 f 05% fiww STATES PATENT OFFICE.

149E153. SRENCER, F HARTFORD, CONNECTICUT, ASSIGNOR TO JOHN J. MOINTYRE,

- "F HARTFORD, CONNECTICUT. a

"To till whom "it may concern:

SPARK-PLUG.

. Specification of Letters Patent.

Patented Apr. 4, 1911.-

Applicatidn filed alanuary 14, 1911. Serial No. 602,605.

Be itknown that I, LOUIS SPENCER, a citizen of ;;the United States,residing at Hartford, in the county of Hartford and State ofConnecticut,have invented a new and useful 'Improvementin Spark Plu gs, of

which the fol lowi-ngis a specification.

This anvention relates to the construction of spark plugs for internalcombustion engines, f

The objeot o'f the invention is to provide a relatively small, simpleand cheap plug which "is efli'cient, durable, and can be readily cleanedand adjusted.

d' g-ure l of the accon'rpanying drawings 'Hshows aside elevation of aplug which enibodies the invention. Fig. 2 shows a central verticalsection of the same. Fig. 3 shows J-a bottom view oftheplug.

Theplug i l' histrated has a hollow cy1indries-1 body 1, which ispreferably made of steel and provided with an exteriorly threaded hub 2,that is designed to be screwed into'the' engine cylinder casing.

' employment of any packing.

Theupper edge of the body has an internally beveled surface 3, and nearthis edge in the interior the body ,is provided with a thread; Screwedinto this interior thread in the body is the threaded end of a thimble4. The thimble is desirably made of soft brass and has an externaltapering surface 5, which when the thimble and body are screwedtogether, is adapted to seat against the internalt-apering surface 3 soas to form ati ht joint between the parts, without the As a result ofthis construction, the body and thimble are always fastened together inthe same relation to each other, for there is no packing "between thetwo, which would have a tendency to yield, and thus vary the relation ofthe parts, and which would be liable to burn out or become ineflicientunder the influence of the heat to which a spark plug body is subjected.

In the lower end of the hub 2 of the body is an opening 6, and spanningthis opening is-a conducting bow 7 provided with a cen an terminal point8.- The opening through the thiinble tapers or contracts from the bottomupwardly, and driven into this opening from the underside is a porcelainbushing 9. This bushing is larger at the bottom than atthe top, thetaper however being slight, so that the bushing may be driven tightlyinto the 'thi-mble. As a result of tapering these parts in this manner,the pressure, incident to explosions of gas in the cylinder, tends todrive the bushing upwardly into a more contracted part of the opening inthe thimbleand thus expand the soft thin'lbleoutwardly and cause thethreaded and tapered joints between the lower end of the thiinble andthe upper end of the body to more tightly closed. l I

Extending through the central opening in thethhnble is a rod 10. Thelowereud of this rod hash 'termiiialvpoint- 11, while the upper'end isprovided with a wire clumping piece 12. A portion of the rod 10 isthreaded, and turning on the threaded part of the rod below the bushingis a nut 13,

and turning on the threaded part abovethe bushing is a nut 14. Micawashers 15, which are'larger in diameter than the bushing, aredesirablyvused between the upper nut 14 and the to of the bushing. Thenuts permit the ro to ,be readily adjusted for the purpose of varyingthe spark gap between the terminal points, when it is desirable or whenit is necessaryto file down one of the points in order to re-forin theend of the terminal. The nuts'also hold the rod firmly in position. Themica washers at the upper end of the bushing being larger in diameterthan the diameter of the bushing, allow the porcelain to be much shorterthan otherwise would be the case, for the washers lengthen the distanceand make abreak in the continuity of the insulating surface be tween theupper nut 14 on the rod-10 and the upper end of the thimble. Thewashersalso form a protection for the upper end of the "fragile porcelainbushing, and prevent it from being chipped or cracked by the tighteningof the nuts, and they also pack the opening through which the'rodextends so that no gass can escape and thus tend to lower thecompression in the cylinder into which the plug is screwed. \Vith thisconstruction the porcelain may be shortened without decreasing theeffectiveness of the insulation, andthus the strength and durability ofthe plug as a whole is increased, and furthermore, it does not take upas much space, for it does not project as far from the cylinder intowhich it is screwed as would otherwise be the case. When the central fcontact carried by the porcelain bushing'is adjusted, if the thimble andbushmore firmly ble andcause same position and the there is nocompressible packing between inglare removed for cleaning the points,the,

parts can tie screwed back to exactly the oints made tight, as

terminal is well separated from the body I and is so protected thatit isnot likely to be sooted by the explosions and become ineificient orpermit localities other The invention claimed is:

1. A spark plug having a with, an exterior thread at one end and aninternal bevel and'an interior thread at the other-end, a conducting bowspanning the thread adapted to fit the upper end-of the :with anexterior 'nuts on the rod aboveand below exteriorly threaded end of thebody, a thimble with an. external bevel and exterior body, said thi'mblehaving a tapering. opening which contracts from the lower end upward, aninsulating-bushing that is largest at its lower end driven upwardly intothe tapering opening in the thnnble, a conducting rod extending throughthe bushing, and the bushing for adjusting the parts with relationtoeach other and the lower end' of the said. rod with relation to thebow at the lower end of the body.

'2. A spark plug having a body provided thread at one end. and anexternal bevel and an interior thread at the other end, a conducting bowspanning the I exteriorly' threaded end of the body, a thim on the rodabove and be ow leakage of current from 3. A spark than at the terminalpoints.

body provided I teriorly threaded opening in the thimble, tendingthrough the bushing, nuts on g the rod above and below the bushing foradjustble with an external bevel and exterior thread adapted to fit theupper end of the body, said thimble having atapering opening whichcontracts from the lower. end upward, an insulating bushing'that islargest at its lower end driven upwardly into the tapering opening inthe thnnble', a conducting rod extending throu h the bushing, nuts thebushing for adjusting the parts with relation to each other and thelower relation to the bow at the lower end ofthe body, and mica washerswhich arelarger in end of the" said rod with Y diameter than thediameter of the bushing located between the upper nut on the 1:0 and theupper end ofthebushingj.

with an exterior other end, a conducting bow spanning the exend of thebody, a thinfible with an external bevel and exterior thread adapted tofit the upper end of the body, said. thimble having a tapering openingwhich contracts from the lower end upward, an insulating bushing that islargest at its lower end driven upwardly into the tapering a conductingrod exing the parts with relation to each other and the lower end of thesaid'rod with relation to t,he. bow at the lower end of the body, a

plug having a body'pro' 'ded thread atone end and aninternal bevel andan interior thread at the terminal point projecting upwardly from thecenter of the bow at the lower end of the body, and a terminal pointprojectmgdownwardly'from the lower end of the rod.

' LOUIS R. SPENCER. lVitnesses i JosnrHmnM. Srnnmrrnn, H. R. VVILLIAMs.

